As is well known, when a baby drinks milk, formula, water or juice from a baby bottle, the baby's sucking action tends to create a vacuum in the bottle, leading to the collapse of the nipple and frequently to the baby being unable to draw more liquid from the bottle. The baby's exertions to keep drinking then become very stressful and also cause the baby to draw much air into its stomach, with adverse results in terms of pain and sleeplessness for both the baby and its parents that any parent of a colicky baby can easily understand.
In an attempt to overcome these problems, baby bottles have heretofore been proposed which include valves at their bottom ends for the express purpose of relieving the vacuum in the bottle either manually or automatically while the baby is drinking from the bottle. Representative constructions of such bottles are shown in U.S. Pat. Nos. 1,732,126 (Gardner); 2,084,099 (Maccoy); 3,768,683 (Van Den Bosch); 4,730,744 and 4,828,126 (Vincinguerra); and 4,928,836 (Wu et al.). For one reason or another, however, these bottles have not found favor in the marketplace, most likely because the valves are difficult and time-consuming to disassemble and clean and thus place an extra strain on the usually already limited time of the baby's mother, and because the valves tend to leak. Still another reason may be that the valves pose a hidden danger to a baby in that the relatively small components of such a valve, should they become inadvertently or accidentally disassembled and fall into the baby's crib or carriage, could be easily taken by the baby into its mouth and swallowed, with potentially disastrous consequences.